| Research Abstract |
Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in BALB/c mice (8-12 wk of age). The DNA binding activity of AP-1, as assessed by electrophoretic mobility shift assay, was time-dependently increased in lung tissues from mice after the onset of CLP-induced sepsis. This increase was effectively eliminated by in vivo transfection of AP-1 decoy oligonucleotides (ODNs). Sepsis induction significantly increased surface expression of death receptors, such as TNF-R1, Fas, DR4, and DR5, in lung and aortic tissues after sepsis. Furthermore, the gene and protein levels of FADD, which recruits procaspase-8 into the death-inducing signaling complex, were increased after sepsis induction. These sepsis-induced changes were eliminated by systemic application of AP-1 decoy ODNs. TUNEL assays revealed that the significant appearance of cell apoptosis in lung and aortic tissue sections from septic mice was prevented by systemic treatment with AP-1 decoy ODNs. When endotoxic shock was induced by an intravenous injection of 10mg/kg lipopolysaccharide (LPS) in mice, expression levels of inflammatory molecules, including IL-1R, IL-6R, HMGB-1, and gp130, were highly increased, which was significantly inhibited by AP-1 decoy ODN treatment. All animals which received LPS died within 48h, and the animals that were treated with AP-1 decoy ODNs after LPS exhibited a striking improvement of survival. Our results suggest that AP-1 decoy ODN therapy represent an effective strategy in the treatment of sepsis. In addition, systemic administration of siRNA targeting FADD, which was found to be transactivated by AP-1, prevented the development of acute lung injury in CLP mice, and improved their survival. These findings indicate the potential usefulness of FADD siRNA for gene therapy of the septic syndrome.
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